fmrx: set baudrate from the program header

Set the baudrate from the divisor in the program header. This requires
that we know when a header block is coming, so reset the baud rate if
the motor relay is turned off.

USBCAS/fmrx.c

@@ -6,12 +6,12 @@
 
 static inline void fmrx_led_on(void)
 {
-  //PORTB &= ~(1 << 0);
+	PORTB &= ~(1 << 0);
 }
 
 static inline void fmrx_led_off(void)
 {
-  //	PORTB |= (1 << 0);
+	PORTB |= (1 << 0);
 }
 
 void fmrx_init(void)
@@ -49,7 +49,7 @@ void fmrx_init(void)
 	/*
 	 * Default speed
 	 */
-	fmrx_set_speed(CAS_BASE_CLOCK/CAS_DIVISOR_ABC80);
+	fmrx_set_speed(CAS_DIVISOR_ABC80);
 }
 
 /* Timing constants: start and end of data bit interval, and timeout */
@@ -74,9 +74,15 @@ static inline void disable_timeout(void)
 	TIFR1 = TIMSK1 = (1 << ICIE1);
 }
 
-void fmrx_set_speed(uint32_t baudrate)
+void fmrx_set_speed(uint8_t divisor)
 {
 	uint8_t prescale = 1;	/* No prescaling */
+	uint32_t baudrate;
+
+	if (!divisor)
+		divisor = CAS_DIVISOR_ABC80;
+
+	baudrate = (CAS_BASE_CLOCK+(divisor >> 1)-1)/divisor;
 
 	/* Enable prescaler for low baud rates to reduce wraparound */
 	if (baudrate < 976) {
@@ -98,6 +104,15 @@ void fmrx_set_speed(uint32_t baudrate)
 	TCCR1B |= prescale;	/* Start timer */
 }
 
+/*
+ * When the motor is switched off, reset the download speed, so
+ * we can load the next header block correctly
+ */
+void fmrx_motor_off(void)
+{
+	fmrx_set_speed(CAS_DIVISOR_ABC80);
+}
+
 /* We "hunt" for a block until we find this bit pattern; same as ABC800 */
 #define CAS_SYNC_PATTERN 0x0216 /* SYNC + STX */
 #define CAS_BLOCK_LEN    (1+2+253+1+2) /* type+num+data+ETX+checksum */
@@ -105,21 +120,51 @@ void fmrx_set_speed(uint32_t baudrate)
 /* Finish a bit due to clock edge or timeout */
 static inline ATTR_ALWAYS_INLINE void finish_bit(void)
 {
+	static uint16_t rx_csum;
+	static uint8_t header;
+	static uint8_t header_divisor;
+
 	if (!started)
 		return;
 
 	if (bytes) {
 		if (--bits == 0) {
 			uint8_t outbyte = data >> 8;
-			fmrx_recv_byte(outbyte);
 			data = 0; /* To avoid false sync */
 			bits = 8;
-			if (--bytes == 0)
+			switch (--bytes) {
+			case 0:
 				fmrx_led_off();
+				if (header)
+					fmrx_set_speed(header_divisor);
+				return;
+			case 1:
+				if (rx_csum != data)
+					set_modem_status(CDC_CONTROL_LINE_IN_PARITYERROR);
+				return;
+			case 2:
+				/* First checksum byte */
+				return;
+			case 3:
+				if (outbyte != 0x03)
+					set_modem_status(CDC_CONTROL_LINE_IN_FRAMEERROR);
+				return;
+			case CAS_BLOCK_LEN-1:
+				header = outbyte;
+				break;
+			case CAS_BLOCK_LEN-3-11-1: /* Byte after filename */
+				header_divisor = outbyte;
+				break;
+			default:
+				break;
+			}
+			rx_csum += outbyte;
+			fmrx_recv_byte(outbyte);
 		}
 	} else if (data == CAS_SYNC_PATTERN) {
 		bits = 8;
 		bytes = CAS_BLOCK_LEN;
+		rx_csum = 0x03;	/* Final ETX */
 		fmrx_led_on();
 	}
 }

USBCAS/fmtx.c

@@ -174,6 +174,13 @@ static uint8_t do_cmd(uint8_t cmd, const uint16_t *arg)
 		/* &U */
 		go_to_bootloader();
 		return rx_idle;
+
+	case 'R':
+		/* Set receive baudrate divisor */
+		/* &R divisor */
+		fmrx_set_speed(arg[0]);
+		return rx_idle;
+
 	case 'H':
 		/* Begin header block */
 		/* &H divisor */
@@ -187,6 +194,7 @@ static uint8_t do_cmd(uint8_t cmd, const uint16_t *arg)
 		rx_blk->pause = 362 << BIT_PATTERN_LEN_LG2;
 		rx_blk->data.blktype = 0;
 		rx_blk->data.blkno = arg[1];
+
 	blk_common:
 		fmtx_drain();
 		fmtx_set_speed(arg[0]);

USBCAS/usbcas.c

@@ -42,7 +42,7 @@
  * Input and output ring buffers
  */
 static RingBuffer_t c2u_ringbuf;	/* CAS -> USB */
-static uint8_t      c2u_buffer[128];
+static uint8_t      c2u_buffer[512];
 
 /**
  * LUFA CDC Class driver interface configuration and state
@@ -111,12 +111,10 @@ bool _motor_relay;
 
 static inline ATTR_ALWAYS_INLINE void motor_led_on(void)
 {
-  //PORTB &= ~(1 << 0);
 }
 
 static inline ATTR_ALWAYS_INLINE void motor_led_off(void)
 {
-  //PORTB |= (1 << 0);
 }
 
 ISR(TIMER3_CAPT_vect)
@@ -140,6 +138,7 @@ ISR(TIMER3_CAPT_vect)
 		} else {
 			_motor_relay = false;
 			motor_led_off();
+			fmrx_motor_off();
 		}
 	}
 }
@@ -149,16 +148,22 @@ ISR(TIMER3_CAPT_vect)
  * or if forced. DSR is always set, DCD indicates if the cassette
  * motor relay is active.
  */
-static void update_modem_status(USB_ClassInfo_CDC_Device_t * const cii,
-				bool forced)
-{
-	uint16_t lines = 0;
+uint16_t _modem_status;
 
-	if (motor_relay()) /* Cassette relay active */
-		lines |= CDC_CONTROL_LINE_IN_DCD | CDC_CONTROL_LINE_IN_DSR;
+static void update_modem_status(void)
+{
+	USB_ClassInfo_CDC_Device_t * const cii = &vcpif;
+/* Clear error bits when the motor is stopped */
+	if (!motor_relay()) {
+		_modem_status = 0;
+	} else {
+		/* Cassette relay active */
+		_modem_status |= CDC_CONTROL_LINE_IN_DCD |
+			CDC_CONTROL_LINE_IN_DSR;
+	}
 
-	if (forced || cii->State.ControlLineStates.DeviceToHost != lines) {
-		cii->State.ControlLineStates.DeviceToHost = lines;
+	if (_modem_status != cii->State.ControlLineStates.DeviceToHost) {
+		cii->State.ControlLineStates.DeviceToHost = _modem_status;
 		CDC_Device_SendControlLineStateChange(cii);
 	}
 }
@@ -169,9 +174,6 @@ static void update_modem_status(USB_ClassInfo_CDC_Device_t * const cii,
  */
 static void usb_run_stack(void)
 {
-	/* Update modem flags if needed */
-	update_modem_status(&vcpif, false);
-
 	CDC_Device_USBTask(&vcpif);
 	USB_USBTask();
 }
@@ -259,6 +261,7 @@ void do_usb_tasks(void)
 {
 	usb_recv_data();
 	usb_send_data();
+	update_modem_status();
 	usb_run_stack();
 }
 
@@ -276,13 +279,10 @@ int main(void)
 
 	GlobalInterruptEnable();
 
-	while (1) {
+	while (1)
 		do_usb_tasks();
-	}
 }
 
-static uint32_t current_baudrate;
-
 /** Configures the board hardware and chip peripherals for the demo's functionality. */
 void SetupHardware(void)
 {
@@ -379,17 +379,19 @@ void EVENT_USB_Device_Disconnect(void)
 /** Event handler for the library USB Configuration Changed event. */
 void EVENT_USB_Device_ConfigurationChanged(void)
 {
-	bool success = true;
+	USB_ClassInfo_CDC_Device_t* const cii = &vcpif;
 
-	success &= CDC_Device_ConfigureEndpoints(&vcpif);
-	if (success)
-		update_modem_status(&vcpif, true);
+	if (CDC_Device_ConfigureEndpoints(cii)) {
+		cii->State.ControlLineStates.DeviceToHost = 0;
+		CDC_Device_SendControlLineStateChange(&vcpif);
+	}
 }
 
 /** Event handler for the library USB Control Request reception event. */
 void EVENT_USB_Device_ControlRequest(void)
 {
-	CDC_Device_ProcessControlRequest(&vcpif);
+	USB_ClassInfo_CDC_Device_t* const cii = &vcpif;
+	CDC_Device_ProcessControlRequest(cii);
 }
 
 /*

USBCAS/usbcas.h

@@ -93,15 +93,21 @@ bool fmtx_full(void);
 void fmtx_recv_byte(uint8_t byte);
 
 extern bool _motor_relay;
-
 static inline ATTR_ALWAYS_INLINE bool motor_relay(void)
 {
 	return _motor_relay;
 }
 
+extern uint16_t _modem_status;
+static inline ATTR_ALWAYS_INLINE void set_modem_status(uint16_t what)
+{
+	_modem_status |= what;
+}
+
 void fmrx_init(void);
-void fmrx_set_speed(uint32_t baudrate);
+void fmrx_set_speed(uint8_t divisor);
 void fmrx_recv_byte(uint8_t byte);
+void fmrx_motor_off(void);
 
 void go_to_bootloader(void);